1. Field of the Invention
The invention concerns an artillery rocket with a course correction unit which is actuated by a satellite receiver.
2. Discussion of the Prior Art
The artillery rocket of the general kind specified is known from DE 43 25 218 C2. This involves an MLRS1-rocket which, to increase its range, is provided with canards in order to be able to extend the falling leg of the ballistic trajectory by virtue of the lift effect of the canards at the ogival head of the rocket structure. So that in that case the error level does not rise to an incompatible degree, the rocket is equipped with a satellite navigation system for correcting the current trajectory, having regard to the predetermined target co-ordinates. Trajectory correction is effected in a dynamic flight mode by variable setting of the canards, depending on the respective position which is just being adopted at that time in space, in the course of the rolling movement of the rocket. As, to provide a stable trajectory, actuation of the canards must always be effected in such a way as to follow the continuous rotation of the rocket, the control complication and expenditure is considerable and correspondingly functionally critical. In addition the amount of space required for installing the drive devices for continuously changing the canard setting and the power supply which is to be made available on board for that purpose are quite considerable.
A version which is modified in relation to the rocket of the artillery rocket system MLRS1 is described in DE 37 39 370 A1. Rockets of that kind are fired from a launch barrel and, immediately after leaving the barrel, are accelerated by way of a rocket drive which is active for a short time, into an aerodynamically stabilised ballistic trajectory which extends relatively flat and along which it performs a slight rolling movement for the purposes of compensating for interference influences due to the launch. A time setting, which is implemented prior to launch, of a time fuse in the tip of the ogival head of the rocket, when the rocket has arrived over the target area, initiates a gas generator which is also disposed in the ogival head, for filling an inflation hose which extends coaxially along the axis of the system through the payload space within the rocket casing. With the increase in the diameter of the inflation hose, the inflation hose presses submunitions which are packed in parallel relationship with the axis in line configurations therearound, from the inside radially outwardly against the rocket casing, and breaks the rocket casing open along desired-rupture locations in order to laterally discharge the stacks of submunitions.
However much the MLRS1 system which was introduced to the consumer years ago has basically proven its worth, there nonetheless still remain problems as to whether the advised target area for expulsion of the submunitions was actually reached within the flight time which was predetermined at the fuse. For, while the environmental influences which apply upon launch can still be incorporated into calculation of the time presetting, by a weapons management system, irregularities in operation of the rocket motor and thereafter in the condition of free flight, depending on the respective wind strength, wind direction and air pressure, mean that numerous forces which could not be already taken into account at the beginning when presetting the flight time not only have a braking effect on the rocket body but in particular also have a deflecting effect thereon. Because of deceleration effects and deviations from the predetermined trajectory, that results in transverse and lateral delivery errors, as departures from the predetermined target position, and that therefore results in the system capability of the rocket carrier for the submunitions being adversely affected.
Admittedly it is known for example from EP 0 418 636 A2, in the case of a spin-stabilised projectile, to implement trajectory correction by means of transverse thrust units, depending on the respective instantaneous active direction thereof, in space. When it acts through the aerodynamic centre of gravity of the projectile, the transverse thrust results in transverse displacement of the trajectory, while when its action is displaced out of the cross-sectional plane of the centre of gravity, depending on the instantaneous spatial position of the projectile, by virtue of tilting of the longitudinal axis, such transverse thrust results in a pitching or yawing movement, with corresponding changes in trajectory. However, in order in that situation not to lose target acquisition, such correction measures also require a search head with an algorithm for active or passive target tracking for target-oriented trajectory correction. This is a very expensive technology; and such target contacting generally cannot be implemented at all if, as in the case of delivering bomblets, the situation involves use in relation to an area target, without a defined target point or a target point which can be captured by sensor means.
In consideration of those aspects, the technical object of the present invention is to be able to provide the MLRS1 artillery rockets which the consumer has in store in a depot with technologically risk-free interventions which can be implemented as easily as possible, in terms of an increase in performance, in regard to more precise delivery of the submunitions.
A design configuration with transverse thrust units corresponding to EP 0 418 636 A2 cannot be considered for the purposes of attaining that object, because that would require interventions into the rocket structure, which would result in an item of equipment which is new in terms of procurement law. As this does not involve an increase in range, the invention also does not involve considering the mechanical and control-technology expenditure and complication involved with a canard control system. Instead, the object of the invention is achieved by carrying out the combination of features in the main claim, whereby the foremost section of the load space in the rocket where the casing already tapers from the hollow-cylindrical structure to the ogival head, is cut off and emptied of submunitions. From the location where the casing is cut off, an additional frame in the form of an axially thick assembly or intermediate plate member in the form of an annual disc, for a course correction unit together with a transverse thrust unit, is inserted, with a rearwardly remaining axial projecting portion, into the interior of the conically tapering ogival head, and riveted to the cut edge of the ogival head. Finally, the rocket casing which rearwardly adjoins the plane in which the casing was cut is riveted onto the frame which then therefore still projects rearwardly with approximately half its height in an annular shape out of the ogival head, whereby the rocket is again ready for use, in its original external configuration.
The transverse thrust unit is provided with an at least single-layer ring of miniaturised pyrotechnic reaction elements which act radially with respect to the longitudinal axis of the rocket. A navigational device is disposed in front of the reaction elements, in the ogival head. Navigation in the sense of tracking the actual trajectory which is actually flown and at least one course correction for finally flying directly to the predetermined delivery co-ordinates is preferably effected by way of a coil antenna for receiving the signals from navigation satellites, with the antenna being let into the substantially conical outside peripheral surface of the ogival head.
The instantaneous roll position in space, which determines the pulse direction for carrying out a predetermined change in direction of the flight of the rocket by means of a given one of the reaction elements which have not yet been consumed in carrying out earlier corrections is to be detected in a particularly reliable fashion, within the course correction unit, without in that respect involving a great deal of apparatus complication and expenditure, in a manner which is known as such, by means of a magnetic sensor which rotates with the rocket and which responds to the magnetic field of the Earth, over the periodicity of the variation in respect of time of the signal amplitude thereof, because it does not operate in dependence on brightness and thus it also operates in particular independently of the weather.
A microprocessor for comparison of the actual and reference positions, which is to be implemented repeatedly during the flight, and for directionally selective triggering of transverse thrust reaction elements for implementing correction requirements when such are established, also readily has the capacity, when the reference position over the target area is reached, to generate the signal for firing the gas generator for expelling the submunitions.